$\begingroup$What alternative would you suggest ? E.g.a methane-air flame in FID would be like e.g using methylchloride as the makeup gas in ECD.$\endgroup$
– PoutnikMay 19 '19 at 12:43

$\begingroup$@Poutnik One alternative would be electric arc ionization. Another extreme UV. What is special about H2?$\endgroup$
– Dirk BruereMay 19 '19 at 13:21

1

$\begingroup$It would be even much worse than methane. The key is to keep as low baseline ionisation as possible. That does not happen with methane flame and definitely not with arc or UV ionisation. With the arc, there would be additionally very high noise, several orders higher than useful signal.$\endgroup$
– PoutnikMay 19 '19 at 13:26

Another fundamental aspect of using hydrogen in gas chromatography is the so-called van Deemter curve. The curve shows the linear velocity of the gas on the x-axis and plate heights on the y-axis. It can be shown that by using hydrogen one can obtain the best efficiency as compared to any other gas.

And of course, hydrogen is required for burning the organic molecules exiting the column. It is a clean flame (no carbon background).